Devices and methods for posterior resection in robotically assisted partial knee arthroplasties

ABSTRACT

A method of positioning posterior resection guides in a three-dimensional coordinate system using robotic arms to perform partial knee arthroplasties comprises connecting a first tracking device for a surgical tracking system of the robotic arm to a femur, connecting a second tracking device for the surgical tracking system of the robotic arm to a tibia, manually positioning the tibia relative to the femur to a desired orientation to perform a posterior resection, manually determining a position for the posterior resection guide to perform the posterior resection, digitizing a reference point for the posterior resection guide in the three-dimensional coordinate system for a location of a feature of the posterior resection guide, moving the posterior resection guide to the location in the three-dimensional coordinate system with the robotic arm, and resecting a posterior portion of a condyle of the femur using the posterior resection guide to guide a cutting instrument.

CLAIM OF PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 17/230,203, filed on Apr. 14, 2021, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 63/010,761, filed on Apr.16, 2020. This application also claims the benefit of U.S. ProvisionalPatent Application Ser. No. 63/435,733, filed on Dec. 28, 2022. Thebenefit of priority of each of which are claimed hereby, and each ofwhich are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure is directed to devices and methods for use inperforming knee arthroplasty, such as total or partial knee replacementprocedures. In a particular example, the devices and methods can be usedto perform posterior resections.

BACKGROUND

Imaging of anatomical features can be useful in preparing for andperforming surgical procedures. For example, patient-specificinstruments can be derived from patient imaging and robotic surgicalsystems can be configured to track anatomy of a patient based onregistration with patient imaging.

Patient-specific instruments have been successfully deployed for manysurgical procedures. By creating three-dimensional (3D) models ofanatomy of a patient from medical images, surgeries can be customizedusing virtual 3D surgical planning for specific patients. The virtual 3Dsurgical planning can be used to produce patient-specific cutting guidesand instruments, which fit over the anatomy of the specific patient in aunique way to allow for precise replication of the planned surgery ascompared to arthroplasty with conventional or standard instrumentation.

In robotic surgical systems, the shape of the anatomy in the patientimaging can be registered with another frame of reference, such as thephysical space of an operating room where the robotic surgical system islocated. Robotic surgical arms can be used to hold various instrumentsin place in a desired orientation relative to both the anatomy andoperating room during a procedure so that movement of an instrument inthe operating room relative to the anatomy can be tracked on theanatomic imaging based on movement of the robotic surgical arm. It is,therefore, desirable to precisely mount instruments to the roboticsurgical arm.

Both patient-specific and robotic surgical procedures have been appliedto knee arthroplasty procedures. Total and partial knee arthroplastiescan be complicated procedures that utilize a plurality of differentinstruments that are switched during the procedure and result in theanatomy being repositioned throughout the procedure, thereby increasingthe time and cost of the procedure. U.S. Pat. No. 10,136,952 to Coutureet al. and Pub. No. US 2018/0116740 to Gogarty et al. describe cuttingguides and instruments for use in knee replacement surgery.

OVERVIEW

The present inventors have recognized, among other things, that problemsto be solved with traditional partial knee arthroplasties involvepositioning of the knee joint in alignment to receive a prostheticdevice that engages the tibia bone and the femur bone. As such, thedepth of the resections of the tibia bone and femur bone must becoordinated to ensure a gap height for proper seating of the prostheticdevice throughout flexion of the knee joint. Maintaining gap height inconventional procedures can be difficult as different guides andinstruments are moved into and out of the surgical site for differentresections, such as a distal cut and a posterior cut of the femur boneand a proximal and sagittal cut of the tibia bone.

The present inventors have also recognized, among other things, thatproblems to be solved with traditional partial knee arthroplastiesinclude the need for having to attach multiple instruments for properlyresecting the tibia bone and the femur bone, particularly the posteriorportion of only one condyle in a partial knee arthroplasty. Each ofthese instruments needs to be properly aligned with the knee joint to,among other things, ensure proper gap height. Use of too manyinstruments can be off-putting for surgeons due to increased complexityand time of the surgeries. Furthermore, surgeries that require multipleinstruments have conventionally been unsuitable for robot-assistedsurgeries due to complexities of having to attach multiple instrumentsto the robotic surgical arm and the need to register each of theseinstruments individually.

The present subject matter can provide a solution to these and otherproblems, such as by providing solutions for allowing surgeons orsurgical planners to plan gap height control for posterior resection ofa single condyle in a partial knee arthroplasty. The solutions caninclude one or more of the following options: A) use robotic surgeryplanning software to adjust an extension gap to suit a flexion gap tomanually position a manual posterior cut guide or to facilitate roboticplacement of a posterior cut guide; B) use a surgical navigation systemto determine a femur rotation axis to properly manually position amanual posterior cut guide or to facilitate robotic placement of aposterior cut guide; C1) use shims to adjust the position of a manualposterior cut guide; C2) use a robotically-guided femur and tibiapartial cut guide block to position a robot-configured posterior cutguide relative to the distal end of a femur; and D) use arobotically-guided femur and tibia partial cut guide block to guide pinholes for a robot-configured posterior cut guide relative to the distalend of a femur. In additional examples, the present subject matter canprovide solutions to these and other problems, such as by providingmethods for digitizing the position of a robotically controlledposterior resection guide involving inserting a gap checker into a gapbetween a proximally resected tibia and a posterior portion of a condyleof a femur to set a gap height and femoral rotation and digitallycorrelate such gap height to the location for a robotically-positionedposterior resection guide to perform a posterior resection to achievethe same gap height and femoral rotation.

In an example, a method for aligning a posterior resection guide with adistal femur surface can comprise positioning a posterior resectionguide adjacent a proximal resected surface of a tibia and a posteriorsurface of a femur for a knee joint in flexion, displaying arepresentation of a distal end of the femur on graphical display,displaying an alignment axis on the representation, engaging a trackingdevice to the posterior resection guide, tracking an anterior tip of theposterior resection guide on a graphical display, and rotating theposterior resection guide to align the anterior tip with the alignmentaxis on the graphical display.

In an additional example, a system for performing femoral resections fora partial knee arthroplasty can comprise a surgical robot comprising anarticulating arm configured to move within a coordinate system for thesurgical robot, a femoral resection guide instrument comprising, acoupler for connecting to the articulating arm, an extension armextending from the coupler, and a resection block attached to theextension arm, and a finishing guide for performing a posteriorresection of a distal femur, wherein the finishing guide is positionableby the surgical robot to determine a thickness and rotation of theposterior cut.

In another example, a method for resecting a distal femur for a partialknee arthroplasty can comprise attaching a resection guide instrument toan articulating arm of a robotic surgical system, moving the resectionguide instrument to an anterior or posterior side of a distal end of afemur, resecting the distal end of the femur to form a distal resectionsurface, moving the resection guide instrument to the distal resectionsurface, drilling holes into the distal resection surface through theguide bores in the resection guide instrument, inserting pins into thedrilled holes, attaching a finishing guide to the inserted pins, andresecting a posterior side of the femur adjacent the distal resectionsurface using the finishing guide to guide a cutting instrument.

In a further example, a method for aligning a posterior resection guidewith a distal resected femur surface can comprise positioning aposterior resection guide adjacent the distal resected femur surface,inserting a flange of the posterior resection guide between a posteriorsurface of a femur and a proximal resected surface of a tibia, movingthe posterior resection guide medial-laterally to observe a rimthickness between an anterior edge of the posterior resection guiderelative to an edge of the distal resected femur surface, andpositioning shims adjacent the flange to vary the rim thickness.

In yet another example, a system for performing femoral resections for apartial knee arthroplasty can comprise a surgical robot, a trackingsystem, a tracker, a finishing guide and a controller. The surgicalrobot can comprise an articulating arm configured to move within acoordinate system for the surgical robot. The tracking system can beconfigured to determine locations of one or more trackers in thecoordinate system. The tracker can be configured to be tracked by thetracking system. The finishing guide can be configured to be coupled tothe articulating arm to perform a posterior resection of a distal femur.The controller for the surgical robot can comprise a communicationdevice configured to receive data from and transmit data to the surgicalrobot and the tracking system, a display device for outputting visualinformation from the surgical robot and the tracking system, and anon-transitory storage medium having computer-readable instructionsstored therein comprising marking digital locations at a distal end anda posterior surface of a distal end of a femur using the tracker,displaying the digital locations of the distal end and posterior surfaceon the display device, plotting a target axis extending through thedistal end and the posterior surface on the display device, projectingthe target axis to an anterior surface of the femur, and moving thearticulating arm to align the finishing guide along the target axis.

In additional examples, a method of positioning a posterior resectionguide in a three-dimensional coordinate system using a robotic arm inorder to perform a partial knee arthroplasty can comprise connecting afirst tracking device for a surgical tracking system of the robotic armto a femur, connecting a second tracking device for the surgicaltracking system of the robotic arm to a tibia, manually positioning thetibia relative to the femur to a desired orientation to perform aposterior resection, manually determining a position for the posteriorresection guide to perform the posterior resection, digitizing areference point for the posterior resection guide in thethree-dimensional coordinate system for a location of a feature of theposterior resection guide, moving the posterior resection guide to thelocation in the three-dimensional coordinate system with the roboticarm, and resecting a posterior portion of a condyle of the femur usingthe posterior resection guide to guide a cutting instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of an operating room including arobot-assisted surgical system comprising a robotic arm, a computingsystem and a tracking system.

FIG. 2 is a schematic view of the robotic arm of FIG. 1 including aresection instrument configured to provide cutting guide functions andserve as a platform for mounting components for additional surgicalsteps, such as can be used to perform a partial knee arthroplasty.

FIG. 3A is a perspective view of a posterior resection guide insertedbetween a femur and a tibia of a knee joint of a patient.

FIG. 3B is a front view of the posterior resection guide of FIG. 3Ainserted between the femur and the tibia.

FIG. 3C is a perspective view of a pointer connected to a trackingdevice.

FIG. 3D shows a target axis illustrated on the distal end of the femurF.

FIG. 4A is a side view of partial knee resection guide positionedagainst a resected distal end of a femur.

FIG. 4B is a perspective view of a tool base for the partial kneeresection guide of FIG. 4A, which is attached to an extension arm.

FIG. 4C is a perspective view of the posterior resection guide of FIG.4A, which can be configured to include an attachment portion forcoupling to a resection instrument.

FIG. 4D is a diagrammatic side view of the posterior resection guide ofFIG. 4C showing an attachment portion.

FIG. 5A is a front view of robot-configured posterior cut guide showinga coupling portion for connecting to a robotically-guided resectioninstrument.

FIG. 5B is a front view of a resection block for a robotically-guidedresection instrument configured to couple to the robot-configuredposterior cut guide of FIG. 5A.

FIG. 6 is a schematic illustration of a surgical planning userinter-face for determining and configuring extension and flexion gapresections for a partial knee arthroplasty.

FIG. 7 is a schematic illustration of a robotic surgical systemincorporating a resection guide instrument and finishing guide adapterof the present application interacting with a tracking system.

FIG. 8 is a block diagram of an example machine upon which any one ormore of the techniques discussed herein may be performed and with whichany of the devices discussed herein may be used in accordance with someembodiments.

FIG. 9 is a perspective view of a knee joint having a gap checkerinserted between a proximal resection of a tibia connected to a firsttracker and a posterior portion of a femur connected to a secondtracker.

FIG. 10 is a perspective view of a knee joint having a gap checkerinserted between a proximal resection of a tibia and a posterior portionof a femur and a tracking device engaged with a proximal surface of thegap checker.

FIG. 11 is a perspective view of a knee joint having a gap checkerinserted between a proximal resection of a tibia and a posterior portionof a femur and a tracking device connected to the gap checker.

FIG. 12 is a perspective view of a knee joint having amanually-positioned posterior resection guide inserted between aproximal resection of a tibia and a posterior portion of a femur.

FIG. 13 is a block diagram of examples of methods for obtainingcoordinates for and positioning a robotically-controlled posteriorresection guide for a partial knee arthroplasty.

DETAILED DESCRIPTION

FIG. 1 illustrates surgical system 100 for operation on surgical area105 of patient 110 in accordance with at least one example of thepresent disclosure. Surgical area 105 in one example can include a jointand, in another example, can be a bone. Surgical area 105 can includeany surgical area of patient 110, including but not limited to theshoulder, knee, head, elbow, thumb, spine, and the like. Surgical system100 can also include robotic system 115 with one or more robotic arms,such as robotic arm 120. As illustrated, robotic system 115 can utilizeonly a single robotic arm. Robotic arm 120 can be a 6 degree-of-freedom(DOF) robot arm, such as the ROSA® robot from Medtech, a Zimmer BiometHoldings, Inc. company. In some examples, robotic arm 120 iscooperatively controlled with surgeon input on the end effector orsurgical instrument, such as surgical instrument 125. In other examples,robotic arm 120 can operate autonomously. While not illustrated in FIG.1 , one or more positionable surgical support arms can be incorporatedinto surgical system 100 to assist in positioning and stabilizinginstruments or anatomy during various procedures.

Each robotic arm 120 can rotate axially and radially and can receive asurgical instrument, or end effector, 125 at distal end 130. Surgicalinstrument 125 can be any surgical instrument adapted for use by therobotic system 115, including, for example, a guide tube, a holderdevice, a gripping device such as a pincer grip, a burring device, areaming device, an impactor device such as a humeral head impactor, apointer, a probe, a cutting guide, an instrument guide, an instrumentholder or a universal instrument adapter device as described herein orthe like. Surgical instrument 125 can be positionable by robotic arm120, which can include multiple robotic joints, such as joints 135, thatallow surgical instrument 125 to be positioned at any desired locationadjacent or within a given surgical area 105. As discussed below,robotic arm 120 can be used with posterior resection guide 300 of FIGS.3A-3D to perform a partial knee arthroplasty using resection guideinstrument 200 (FIG. 2 ). Robotic arm 120 can additionally be used withthe instruments of FIGS. 4A-4D and FIGS. 5A and 5B. Furthermore, thesurgical planning interface of FIG. 6 can be used in conjunction withrobotic arm 120.

Robotic system 115 can also include computing system 140 that canoperate robotic arm 120 and surgical instrument 125. Computing system140 can include at least memory, a processing unit, and user inputdevices, as will be described herein. Computing system 140 and trackingsystem 165 can also include human interface devices 145 for providingimages for a surgeon to be used during surgery. Computing system 140 isillustrated as a separate standalone system, but in some examplescomputing system 140 can be integrated into robotic system 115. Humaninterface devices 145 can provide images, including but not limited tothree-dimensional images of bones, including tibia T and femur F ofFIGS. 9-12 , glenoids, knees, joints, and the like. Human interfacedevices 145 can include associated input mechanisms, such as a touchscreen, foot pedals, or other input devices compatible with a surgicalenvironment.

Computing system 140 can receive pre-operative, intra-operative andpost-operative medical images. These images can be received in anymanner and the images can include, but are not limited to, computedtomography (CT) scans, magnetic resonance imaging (MRI), two-dimensionalx-rays, three-dimensional x-rays, ultrasound, and the like. These imagesin one example can be sent via a server as files attached to an email.In another example the images can be stored on an external memory devicesuch as a memory stick and coupled to a USB port of the robotic systemto be uploaded into the processing unit. In yet other examples, theimages can be accessed over a network by computing system 140 from aremote storage device or service.

After receiving one or more images, computing system 140 can generateone or more virtual models related to surgical area 105. Alternatively,computing system 140 can receive virtual models of the anatomy of thepatient prepared remotely. Specifically, a virtual model of the anatomyof patient 110, including tibia T and femur F of FIGS. 9-12 , can becreated by defining anatomical points within the image(s) and/or byfitting a statistical anatomical model to the image data. The virtualmodel, along with virtual representations of implants and instrumentssuch as posterior resection guide 430 of FIGS. 4C and 4D, posteriorresection guide 500 of FIG. 5A, posterior resection guide 300 of FIGS.3B and 12 and gap checkers 802 and 860 of FIGS. 9-11 , can be used forcalculations related to the desired location, height, depth, inclinationangle, or version angle of an implant, stem, acetabular cup, glenoidcup, total ankle prosthetic, total and partial knee prosthetics,surgical instrument, or the like to be utilized in surgical area 105. Inanother procedure type, the virtual model can be utilized to determineresection locations on femur and tibia bones for a partial kneearthroplasty, such as the location of virtual cut plane 848 of FIGS. 9and 10 . In a specific example, the virtual model can be used todetermine a gap height for posterior femoral resections (e.g., posteriorcut and chamfer cuts) relative to a proximally resected tibia. Thevirtual model can also be used to determine bone dimensions, implantdimensions, bone fragment dimensions, bone fragment arrangements, andthe like. Any model generated, including three-dimensional models, canbe displayed on human interface devices 145 for reference during asurgery or used by robotic system 115 to determine motions, actions, andoperations of robotic arm 120 or surgical instrument 125. Knowntechniques for creating virtual bone models can be utilized, such asthose discussed in U.S. Pat. No. 9,675,461, titled “Deformablearticulating templates” or U.S. Pat. No. 8,884,618, titled “Method ofgenerating a patient-specific bone shell” both by Mohamed RashwanMahfouz, as well as other techniques known in the art.

Computing system 140 can also communicate with tracking system 165 thatcan be operated by computing system 140 as a stand-alone unit. Surgicalsystem 100 can utilize the Polaris optical tracking system from NorthernDigital, Inc. of Waterloo, Ontario, Canada. Additionally, trackingsystem 165 can comprise the tracking system shown and described in Pub.No. US 2017/0312035, titled “Surgical System Having Assisted Navigation”to Brian M. May, which is hereby incorporated by this reference in itsentirety. Tracking system 165 can monitor a plurality of trackingelements, such as tracking elements 170, affixed to objects of interestto track locations of multiple objects within the surgical field.Tracking system 165 can function to create a virtual three-dimensionalcoordinate system within the surgical field for tracking patientanatomy, surgical instruments, or portions of robotic system 115.Tracking elements 170 can be tracking frames including multiple IRreflective tracking spheres, or similar optically tracked markerdevices. In one example, tracking elements 170 can be placed on oradjacent one or more bones of patient 110. In other examples, trackingelements 170 can be placed on robotic arm 120, surgical instrument 125,and/or an implant to accurately track positions within the virtualcoordinate system associated with surgical system 100. In each instancetracking elements 170 can provide position data, such as patientposition, bone position, joint position, robotic arm position, implantposition, or the like. Examples of tracking elements suitable for usewith computing system 140 can include tracker device 842 and trackerdevice 846 of FIG. 9 , tracker device 854 of FIG. 10 , tracker device874 of FIG. 11 , and tracker device 884 of FIG. 12 .

Robotic system 115 can include various additional sensors and guidedevices. For example, robotic system 115 can include one or more forcesensors, such as force sensor 180. Force sensor 180 can provideadditional force data or information to computing system 140 of roboticsystem 115. Force sensor 180 can be used by a surgeon to cooperativelymove robotic arm 120. For example, force sensor 180 can be used tomonitor impact or implantation forces during certain operations, such asinsertion of an implant stem into a humeral canal. Monitoring forces canassist in preventing negative outcomes through force fitting components.In other examples, force sensor 180 can provide information onsoft-tissue tension in the tissues surrounding a target joint. Incertain examples, robotic system 115 can also include laser pointer 185that can generate a laser beam or array that is used for alignment ofimplants during surgical procedures.

In order to ensure that computing system 140 is moving robotic arm 120in a known and fixed relationship to surgical area 105 and patient 110,the space of surgical area 105 and patient 110 can be registered tocomputing system 140 via a registration process involving registeringfiducial markers attached to patient 110 with corresponding images ofthe markers in patient 110 recorded preoperatively or just prior to asurgical procedure. For example, a plurality of fiducial markers, suchas first tracker 806 and second tracker 810 of FIG. 9 , can be attachedto patient 110, images of patient 110 with the fiducial markers can betaken or obtained and stored within a memory device of computing system140. Subsequently, patient 110 with the fiducial markers can be movedinto, if not already there because of the imaging, surgical area 105 androbotic arm 120 can touch each of the fiducial markers. Engagement ofeach of the fiducial markers can be cross-referenced with, or registeredto, the location of the same fiducial marker in the images. Inadditional examples, patient 110 and medical images of the patient canbe registered in real space using contactless methods, such as by usinga laser rangefinder held by robotic arm 120 and a surface matchingalgorithm that can match the surface of the patient from scanning of thelaser rangefinder and the surface of the patient in the medical images.As such, the real-world, three-dimensional geometry of the anatomyattached to the fiducial markers can be correlated to the anatomy in theimages and movements of instrument 125 attached to robotic arm 120 basedon the images will correspondingly occur in surgical area 105.

Subsequently, other instruments and devices attached to surgical system100 can be positioned by robotic arm 120 into a known and desiredorientation relative to the anatomy. For example, robotic arm 120 can becoupled to resection guide instrument 200 of FIG. 2 , posteriorresection guide 430 of FIGS. 4C and 4D, and posterior resection guide500 of FIG. 5A, that can be used to guide resections on multiple bones(e.g., proximal tibia and distal femur) and that allows otherinstruments (e.g., a finishing guide or posterior cut guide) to beattached to robotic arm without having to individually couple eachinstrument to robotic arm in succession and without the need forindividually registering each attached instrument with the coordinatesystem. As discussed with reference to FIGS. 7 and 8 , memory forcomputing system 140, e.g., memory 1704, can include geometricinformation for instruments and gap checkers described herein so thatthe specific location of each instrument and gap checker, and specificfeatures thereof, can be determined and known by computing system 140when attached to robotic arm 120. Robotic arm 120 can move resectionguide instrument 200 relative to anatomy of the patient such that thesurgeon can, after adding and removing another instrument to the guideinstrument as needed, perform the desired interaction with the patientat specific locations called for by the surgical plan with the attachedinstrument.

FIG. 2 is a schematic view of robotic arm 120 of FIG. 1 includingresection guide instrument 200, which can be positioned by robotic arm120 relative to surgical area 105 (FIG. 1 ) in a desired orientationaccording to a surgical plan, such as a plan based on preoperativeimaging or based, at least partially, on intra-operative planning suchas is described with reference to FIG. 3D. Resection guide instrument200 can comprise tool base 202, extension arm 204 and guide block 206.Extension arm 204 can comprise first segment 208 and second segment 210,as well as additional segments in other examples. Guide block 206 cancomprise body 212, guide surface 214 and interface 216. In an example,guide block 206 can be configured as a resection block for use in apartial knee arthroplasty and, as such, guide block 206 can be used toperform a proximal resection of a tibial plateau and a distal resectionof a femoral condyle. Further, other instruments, such as posteriorresection guide 430 (FIG. 4C) and posterior resection guide 500 (FIG.5A), can be coupled to guide block 206.

Robotic arm 120 can include joint 135A that permits rotation about axis216A, joint 135B that can permit rotation about axis 216B, joint 135Cthat can permit rotation about axis 216C and joint 135D that can permitrotation about axis 216D.

In order to position resection guide instrument 200 relative to anatomyof patient 110 (FIG. 1 ), surgical system 100 (FIG. 1 ) can manipulaterobotic arm 120 automatically by computing system 140 or a surgeonmanually operating computing system 140 to move resection guideinstrument 200 to the desired location, e.g., a location called for by asurgical plan to align an instrument relative to the anatomy. Forexample, robotic arm 120 can be manipulated along axes 216A-216D toposition resection guide instrument 200 such that guide block 206 islocated in a desired location relative to the anatomy. As such, a stepof a surgical procedure can be performed, such as by using guide surface214. However, subsequent steps of the surgical procedure can beperformed with resection guide instrument 200 without having to uncoupleinstrument 200 from robotic arm 120. For example, other instruments canbe attached to guide block 206 at interface 216. Other instrumentsattached at interface 216 can be used without having to re-register anadditional instrument to the coordinate system because the dimensionsand geometries of resection guide instrument 200 and other instrumentsto be used therewith, as well as other instruments and devices describedherein with reference to FIGS. 3A-5B and 9-12 , can be known by surgicalsystem 100 (FIG. 1 ), such as by having physical dimensions forgeometries of such devices being stored in memory, such that thelocations of guide block 206 and instruments attached thereto can becalculated by surgical system 100 as robotic arm 120 moves throughoutthe coordinate system. Stated another way, the location of axis 216Awithin surgical area 105 can be known to computing system 140. Thelocation of tool base 202 within surgical area 105 can be calculatedbased on computing system 140 knowing the dimensions of robotic arm 120and the relative positions portions of robotic arm 120 at axes 216A,216B, 216C and 216D. The locations of instruments attached to tool base202 can be known to computing system 140 based on computing system 140knowing the dimensions and shape of each instrument.

Robotic arm 120 can be separately registered to the coordinate system ofsurgical system 100, such via use of a tracking element 170 (FIG. 1 ).Fiducial markers can additionally be separately registered to thecoordinate system of surgical system 100 via engagement with a probehaving a tracking element 170 attached thereto. Resection guideinstrument 200 can be registered to the coordinate system via couplingwith robotic arm. Other components, such as pointer 326 (FIGS. 3B and3C) and posterior resection guide (FIGS. 4C and 4D), can be registeredusing tracking elements 170 (FIG. 1 ) and tracking element 708 (FIG. 7). As such, some or all of the components of surgical system 100 can beindividually registered to the coordinate system (with or without theaid of tracking elements) and, if desired, movement of such componentscan be continuously or intermittently tracked with a tracking element170.

In some robotic procedures, instruments can be separately andindividually tracked using an optical navigation system that, underideal conditions, alleviate the need for precisely maintaining axis 216Dand the location of an instrument along axis 216D through a surgicalprocedure or surgical task, as the optical navigation system can providethe surgical computer system information to compensate for any changes.However, as optical navigation systems require line-of-sight with theinstruments to be maintained, there is a significant advantage in notrequiring instruments to be navigated (or at least not constantlynavigated). Resection guide instrument 200 allows multiple instrumentsto be registered to robotic system 115 without the need for individuallytracking each instrument. Robotic system 115 can know the preciselocation of robotic arm 120, and the geometry and dimensions ofresection guide instrument 200 can be registered to robotic system 115,such as by being in communication with computing system 140. As such,the location of guide block 206 in the surgical space can be determinedas robotic arm 120 moves guide block 206 within the surgical space.Furthermore, robotic system 115 can be provided, such as within anon-transient computer-readable storage medium, with the geometry anddimensions of instruments configured to be attached to guide block 206such that the locations of attachment instruments can also be tracked asrobotic arm 120 moves. Thus, individual tracking or registration of theattachment instruments can be avoided if desired.

FIGS. 3A-3D illustrate instruments and methods for determining a femurrotation axis for a partial knee arthroplasty. FIGS. 3A-3D illustratedevices and methods for using use a surgical navigation system todetermine a femur rotation axis to properly manually position aposterior cut guide or to facilitate robot-guided posterior cut guideplacement, which in turn allows from proper rotational positioning of afemoral implant. In a specific example, the posterior resection cutguide can be a device configured to be manually positioned and aligned.Typically, such devices are aligned using surgeon skill and experienceby visually evaluating the position of the device relative to thedistally resected femur. FIG. 3D illustrates a method for using anavigation system to determine an axis along the femur that can be usedto align the posterior cut guide manually or with the aid of a robot.

FIG. 3A is a perspective view of posterior resection guide 300 insertedbetween femur F and tibia T. Handle 302 can be connected to posteriorresection guide 300. In the illustrated example, posterior resectionguide 300 comprises a uni-condylar resection guide configured to guide aresection along a posterior portion of a single condyle at a distal endof femur F. Posterior resection guide 300 can comprise body 304 andflange 306. Body 304 can be configured for coupling to handle 302, suchas by including a socket or adapter that receives a mating component onhandle 302. Body 304 can additionally include features for guidingcutting instruments or other instruments against femur F. For example,body 304 can include posterior cut guide surface 308, chamfer cut guidesurface 310, anterior peg guide hole 312, posterior peg guide hole 314and pin holes 316A, 316B and 316C. Femur F includes distal resectedsurface 318 and tibia T includes proximal resected surface 320.

Posterior resection guide 300 can be inserted between femur F and tibiaT such that flange 306 contacts proximal resected surface 320 and body304 contacts distal resected surface 318. A set of posterior resectionguides 300 can be provided with each having body 304 with differentsizes configured to implant different sized prosthetic components fordifferent sized bones. Posterior resection guide 300 can also bereferred to as a finishing guide because other features of body 304 canbe used to finish the distal end of femur F to receive a prostheticdevice. For example, chamfer cut guide surface 310 can be used toperform a chamfer resection that forms an angled surface betweenresected surface 318 and the surface formed with cut guide surface 308.Also, guide holes 312 and 314 can be used to drill holes to receivefixation features, e.g., pegs, of a prosthetic device such as auni-condylar prosthetic device. Pin holes 316A-316B can be used toinsert pins or pegs into resected surface 318 to temporarily affixposterior resection guide 300 to femur F while the bone is beingmodified using posterior resection guide 300, such as to stabilize thecuts being performed.

FIG. 3B is a front view of posterior resection guide 300 insertedbetween femur F and tibia T. The location of posterior resection guide300 can be visually inspected to determine the location of body 304against distal resected surface 318 by evaluating the distance betweenthe edge of distal resected surface 318 and body 304, which can affectthe thickness of the posterior cut and resulting rotation of the femoralcomponent. In examples, shims can be positioned adjacent flange 306 tovary the amount of bone that is resected along the posterior cut. Forexample, shims of predetermined thicknesses can be used individually orstacked to vary the distance between body 304 and the edge of resectedsurface 318, such as by placing the shims below flange 306.Additionally, shims can be positioned on top of flange 306 to vary thedistance between the edge of distal resected surface 318 and body 304.In additional examples, flange 306 can be omitted from posteriorresection guide 300, or as in other examples described herein, in orderto allow for the use of shims without accommodating flange 306. Whenproperly sized, there is typically a rim of at least 2 mm of exposedbone between the edge of distal resected surface 318 and body 304.However, sometimes it is difficult to evaluate the position of posteriorresection guide 300 due to engagement between the non-resected condyleand the non-resected portion of the proximal end of tibia T causing apivoting action between the resected portions, as well as tissue of thepatient obstructing visibility. In the present disclosure, pointer 326can be used to facilitate alignment of posterior resection guide 300,such as where anterior tip 324 is placed medial-laterally on distalresected surface 318 or where the outer profile of guide 300 sits on thedistal resected surface 318.

FIG. 3C is a perspective view of pointer 326. Pointer 326 can comprisetip 328, shaft 330 and tracking device 332. Pointer 326 can comprise adevice for contacting specific locations in the coordinate system ofrobotic system 115 (or computing system 140) using tracking device 332.Tracking device 332 can comprise a tracking array, such as trackingelement 170 of FIG. 1 , that can provide location information to roboticsystem 115. Tracking device 332 can be inserted into socket 334 andsecured thereto by a pin or the like to fix the location of trackingdevice 332 relative to tip 328. Tip 328 can comprise a pointed end ofshaft 330 that can be used to engage tissue of a patient to marklocations for the coordinate system of robotic system 115. In otherexamples, other instruments having preconfigured or fixed geometricshapes can be used in conjunction with a tracking device to marklocations for the coordinate system. Tip 328 can be pressed into bone,for example, while tracking device 332 provides a reading to surgicalsystem 100. Thus, tracking device 332 can provide an indication of thelocation of pointer axis 336 to robotic system 115. Pointer 326 canfurther comprise handle 338. Handle 338 can provide an ergonomic gripfor pointer 326 to allow manipulation by a surgeon. In order to increasethe accuracy of the registration process, it is desirable for pointershaft 330 to extend over a length to increase the location reading ofaxis 336 taken at tip 328. It is also desirable for handle 338 to belocated close to tip 328 to allow a surgeon to easily place tip 328where desired.

Posterior resection guide 300 can be engaged with pointer 326 to trackthe position and orientation of posterior resection guide 300 relativeto femur F. In particular, pointer 326 can be used to align posteriorresection guide 300 with target axis 340 (FIG. 3C) to facilitatealigning of posterior resection guide 300 for determining proper gapheight.

FIG. 3D shows target axis 340 illustrated on distal end of femur F. Inan example, target axis 340 could be determined preoperatively usingimaging of the patient of femur F and tibia T using, for example, knowntechniques. In other examples according to the present disclosure,target axis 340 can be determined intra-operatively. Target axis 340 canbe determined before the distal end of femur F is resected to remove anycondyles. For example, target axis 340 can be determined before eitherof femur F and tibia T are resected, or after tibia T is resected toform proximal resected surface 320 and with shim 342 insertedtherebetween.

Target axis 340 can comprise distal point 344 and posterior point 346.Distal point 344 can be determined, identified and marked with tibia Tplaced in extension relative to femur F. A physical mark can be placedon femur F or a digital mark can be placed on an image of femur F at thelocation where the tibia plateau of tibia T contacts the condyle offemur F using robotic system 115 (or computing system 140). A marker canbe used to draw on femur F or a scoring device, such as a pin, can beused to scratch an indentation in femur F. Additionally, pointer 326 canbe used to digitally mark the location of distal point 344 by engagingtip 328 with the engagement point between the tibial plateau and thecondyle. Next, tibia T can be rotated into a flexion position relativeto femur F such that posterior point 346 can be determined, identifiedand marked, either physically or digitally using a similar method as wasused to mark distal point 344. Line 348 can be extended between distalpoint 344 and posterior point 346 to facilitate projection of thelocation for anterior point 350. The projection of line 348 can befollowed up the anterior side of femur F to anterior point 350 to findthe rotational, e.g., medial-lateral, location for anterior tip 324 forbody 304 of posterior resection guide 300, which allows for properrotational placement of a femoral implant installed according to drilledholes and the like with posterior resection guide 300. For example,pointer 326 can be engaged with tip 324 and posterior resection guide300 can be internally-externally rotated until tip 324 is positioned onthe extension of line 348 or the outer profile of guide 300appropriately covers the distal resected surface 318, thereby indicatingthe proper position for posterior resection guide 300. For example, adigital representation of pointer axis 336 can be displayed on a userinterface device (e.g., user or human interface device 145 of FIG. 1 )to facilitate alignment with a digitally generated version of targetaxis 340 also shown on the user interface device. Also, the physicaldevice of posterior resection guide 300 can be aligned with the physicalline scored or drawn on femur F. In other examples, a tracking devicesuch as pointer 326 can be directly coupled to posterior resection guide300, rather than simply engaged with tip 324, such as by insertion intoa socket or threaded bore, as explained in greater detail with referenceto FIG. 12 . Thus, 1) in a first example, line 348 and point 350 can bephysically drawn on the distal end of the femur using a marking pen, theposition of posterior resection guide 300 can be manually positioned bya surgeon against the femur, with or without the use of shims, andpointer 326 can be used to digitize the location of point 350 atanterior tip 324 to generate location information for the guidance ofrobotic arm 120 to position posterior resection guide 300, and 2) in asecond example, a digital line (or plurality of discretely takenlandmarks) can be drawn on the distal end of the femur using pointer 326to digitize line 348 and point 350 on a display screen, the position ofposterior resection guide 300 can be physically positioned by a surgeonwhile connected to tracker device 370 to move anterior tip 324 intoalignment with point 350 on the display screen to generate locationinformation for the guidance of robotic arm 120 to position posteriorresection guide 300. Although described with reference to aligninganterior tip 324 with point 350, the description of FIGS. 3A-3D can beapplied to appropriately locating and/or orienting any componentsdescribed herein, such as cut guides, spacer blocks, shims and gapcheckers. The procedures described herein can have the followinggoals: 1) aligning the femur perpendicular to the tibial component whenin flexion, 2) sizing and locating the femur appropriately so as to notoverhang the distal cut surface 318, and 3) rotating the femur toprovide appropriate interior/exterior rotation to serve the needs of thepatella.

FIG. 4A is a side view of partial knee resection guide 400 positionedagainst a resected distal end of femur F. FIG. 4B is a perspective viewof tool base 402 of partial knee resection guide 400 attached toextension arm 404. FIGS. 4A and 4B are discussed concurrently. Inexamples, partial knee resection guide 400 can be configured similarlyto cut guides disclosed in U.S. Pat. No. 10,136,952 to Couture et al.and Pub. No. US 2018/0116740 to Gogarty et al.

Partial knee resection guide 400 can comprise tool base 402, extensionarm 404 and resection block 406, which can comprise a resection blockfor resecting the distal portion of femur F, the proximal portion oftibia T and for mounting posterior resection guide 300 (FIGS. 3A-3B) andvariations thereof (FIGS. 4C and 5A). Resection block 406 can compriseboth an instrument and an adapter for attaching other instruments toextension arm 404 and, hence, robotic arm 120. For example, guidesurface 408 can comprise a slot for guiding or otherwise engaging acutting instrument such as a reciprocating or oscillating saw blade tocut bone, such as a superior portion of tibia T and a distal portion offemur F. Interface 410 (FIG. 4C) can comprise features that facilitateattachment of other instruments to resection block 406, such as ports,plugs, receptacles, threaded couplers, slots and the like. In examples,interface 410 (FIG. 4C) can comprise one or more through-bores, threadedbores, dovetail slots, pins, detents, chuck mechanisms and collets, andcombinations thereof.

Tool base 402 (FIG. 4B) can comprise pedestal 412 from which extensionarm 404 can extend, mounting slots 414A and 414B and fasteners 416A and416B. Tool base 402 can be coupled to robotic arm 120 by insertingfasteners 416A and 416B through mounting slots 414A and 414B and intomating bores in robotic arm 120. Slot 418 can receive an alignmentfeature on robotic arm 120 to ensure proper mounting of tool base 402.

Extension arm 404 can comprise first segment 420 and second segment 422,as well as other segments to position resection block 406 relative totool base 402. Segments 420 and 422 can comprise elongate rigid membersextending from tool base 402 in an end-to-end fashion. Segments 420 and422 can be configured to hold resection block 406 in a fixed positionrelative to tool base 402. Such positional relationship can be stored ina non-transient computer-readable storage medium for robotic system 115or computing system 140. Segments 420 and 422 can be tubular or solidbodies that are angled relative to each other to position resectionblock 406 relative to tool base 402, such as in a position conducive fora surgeon to access resection block 406 while robotic arm 120 is out ofthe way of the surgeon. In an example, first segment 420 can extend fromtool base 412 perpendicular, or approximately perpendicular, to frontsurface 423 of tool base 412 (FIG. 4A). In other examples, segments 420and 422 can comprise curved segments. In various examples, segments 420and 422 can lie in a common plane or can be in planes oblique to eachother. Additionally, other distal segments at the end of segment 422 cantaper down toward resection block 406 to reduce the footprint againstresection block 506.

Resection block 406 can comprise body 424 that provides a platform forguide surface 408 and interface 410. Body 424 can further comprise bores426A and 426B that can define interface 410 (FIG. 4C).

With reference to FIG. 4C, guide surface 408 can comprise a planarsurface against which a cutting instrument can be engaged to perform acutting procedure. In the illustrated example, guide surface 408 cancomprise a slot that is bounded on four sides, e.g., front body 424 canprovide upper, lower and lateral sides around guide surface 408.However, in other examples, guide surface 408 can comprise an unboundedledge or a partially bounded ledge, e.g., a partial slot. Guide surface408 can be located toward a side of body 424 to increase visibility ofanatomy behind resection block 406. For example, guide surface 408 canbe located proximate to a top surface such that a surgeon can viewanatomy over the top of resection block 406 while simultaneouslyallowing the lower portion of body 424 to include bores 426A and 426Bfor interface 410. Guide surface 408 can be sized, e.g., have a width,suitable for resecting a single femoral condyle Or half of a tibialplateau.

Bores 426A and 426B can comprise through bores extending from a frontsurface of body 424 all the way through to a rear surface of body 424.Bores 426A and 426B can thus provide ports for inserting pins throughbody 424 and into the anatomy of the patient. The pins can be used to,for example, anchor resection block 406 while cutting of bone occurs toensure a straight cut. Additionally, bores 426A and 426B can comprise aportion of interface 410.

Interface 410 and guide surface 408 can also comprise means forfacilitating coupling of another instrument to resection block 406. Inother examples, interface 410 can comprise a socket having one or morereceptacles for receiving mating components on an additional instrument.In the illustrated example, interface 410 can comprise bores 426A and426B. Bores 426A and 426B can comprise multiple points of contactbetween resection block 406 and a mating instrument to facilitaterotational alignment. In examples, one or more of bores 426A and 426Bcan be threaded to receive a complimentary threaded shaft or fastener.For example, bores 426A and 426B can be threaded to receive a threadedfastener extending from an additional instrument or can be simplethrough-bores to receive alignment prongs of the additional instrument.

FIG. 4C is a perspective view of posterior resection guide 430comprising attachment portion 432. FIG. 4D is a diagrammatic side viewof posterior resection guide 430 of FIG. 4C. FIGS. 4C and 4D arediscussed concurrently.

Posterior resection guide 430 can be configured similarly as posteriorresection guide 300 of FIGS. 3A and 3B except for the omission of flange306 and the inclusion of attachment portion 432. As such, posteriorresection guide 430 can comprise body 433, posterior cut guide surface434, chamfer cut guide surface 436, anterior peg guide hole 438 andposterior peg guide hole 440. Posterior resection guide 430 can includeattachment portion 432 that can comprise superior extension 442,coupling flange 444 and tabs 446A and 446B. Attachment portion 432 canbe used to couple posterior resection guide 430 to resection block 406.For example, coupling flange 444 can be inserted into guide surface 408and/or tabs 446A and 446B can be inserted into bores 426A and 426B,respectively. Coupling flange 444 and tabs 446A and 446B can be usedseparately or together in various examples of posterior resection guide430. In another example, one or both of coupling flange 444 and tabs446A and 446B can be omitted and superior extension 442 can be insertedinto a slot within body 424. Attachment portion 432 can be integral withbody 433 or can be a separate component attached thereto.

Attachment portion 432 thus allows posterior resection guide 430 to becoupled to resection block 406 and, therefore, robotic arm 120. As such,posterior resection guide 430 can be robotically positioned within thecoordinate system of robotic arm 120 relative to femur F, therebyeliminating the manual positioning of a posterior resection guide, suchas posterior resection guide 300. Robotic system 115 can know theprecise location of robotic arm 120, and the geometry and dimensions ofpartial knee resection guide 400 can be registered to robotic system 115and computing system 140. As such, the location of posterior resectionguide 430, and the dimensions and locations of features therein, in thesurgical space can be determined as robotic arm 120 moves posteriorresection guide 430 within the surgical space. Robotic arm 120 cantherefore align posterior resection guide 430 to set posterior resectionguide 430 for a desired flexion gap. In order to eliminate interferencewith undesirably contacting femur F, posterior resection guide 430 doesnot include a flange like flange 306 (FIG. 3A). Thus, posteriorresection guide 430 can be positioned along a distal resected femursurface at any position to control the gap height between the proximalresected tibia surface and the posterior resected femur surface, basedon a surgical plan or surgeon determination without being bound by thethickness of a flanges, such as flange 306. Robotic arm 120 can holdposterior resection guide 430 in place while resections to femur F aremade. In an example, robotic arm 120 can position posterior resectionguide 430 to align with target axis 340 that is intraoperatively plannedwith robotic system 115. Pins can be placed through posterior resectionguide 430, such as at bore 448, and into femur F to stabilize posteriorresection guide 430 in-place at a desired location to perform theposterior resection.

FIG. 5A is a front view of robot-configured posterior resection guide500 showing a coupling portion for connecting to a robotically-guidedresection instrument. FIG. 5B is a front view of a resection block forrobotically-guided partial knee resection guide 502 configured to coupleto robot-configured posterior resection guide 500 of FIG. 5A.

Posterior resection guide 500 can comprise body 503 and mounting flange504. Posterior resection guide 500 can be configured similarly asposterior resection guide 300 of FIGS. 3A and 3B except for the omissionof flange 306. Posterior resection guide 500 can be configured similarlyas posterior resection guide 430 of FIGS. 4C and 4D except for theinclusion of mounting flange 504 instead of attachment portion 432 andthe addition of bores 514A and 514C.

Body 503 can be configured for coupling to partial knee resection guide502, such as by including mounting flange 504 or other featuresconfigured to interact with partial knee resection guide 502. Body 503can additionally include features for guiding cutting instruments orother instruments against femur F. For example, body 503 can includeposterior cut guide surface 508, chamfer cut guide surface 508, anteriorpeg guide hole 510, posterior peg guide hole 512 and bores 514A, 514Band 514C.

Partial knee resection guide 502 can comprise extension arm 516, whichcan connect to a tool base similar to tool base 402 of FIG. 4B, andadapter block 518, which can comprise a resection block for resectingthe distal portion of femur F, the proximal portion of tibia T and formounting or aligning posterior resection guide 500.

Adapter block 518 can comprise body 520, guide surface 522, bores 524A,524B and 524C, and bores 526A, 526B and 526C. Bores 524A-524C and bores526A-526C can be configured to align with bores 514A-514C, respectively.That is, bores 524A-524C can align with bores 514A-514C when posteriorresection guide 500 is positioned on one side of body 520 and bores526A-526C can align with bores 514A-514C when posterior resection guide500 is positioned on one side of body 520.

In examples, fasteners can be used to couple posterior resection guide500 to adapter block 518 at bores 514A-514C, bores 524A-524C and bores526A-526C. In other examples, adapter block 518 can be moved intoposition relative to a distal resected femur surface and pin holes canbe drilled through bores 524A-524C or bores 526A-526C, adapter block518, can be moved away from the distal resected femur, pins can beplaced into the pin holes, and posterior resection guide 500 can becoupled to the pins using bores 514A-514C such that posterior resectionguide 500 can be used to perform the resections of femur F. Such aprocedure, e.g., the use of placed pins with resection guide 502, hasthe benefit of not having to move partial knee resection guide 502 awayfrom femur F to couple to posterior resection guide 500, and then bemoved back into place. Furthermore, such a procedure eliminatestolerance staking of the placement of resection guide 502 relative tofemur F plus the placement of posterior resection guide 500 relative toresection guide 502.

FIG. 6 is a schematic illustration of surgical planning user interface600 for determining and configuring a flexion gap resection for apartial knee arthroplasty. User interface 600 can include input 602 forselecting a position of a knee joint, such as extension or flexion. Theflexion position can be used to determine the posterior resection of thefemur. Input 604 can be used to select a total thickness of a kneeimplant, including the thicknesses of the femoral component, tibialcomponent and a spacer for positioning therebetween, all for auni-condylar or partial knee system. Input 606 can be used to select atotal thickness of bone to be removed from the joint. Output 608 canindicate an amount of space remaining in the joint, taking into accountthe amount of bone removed, the thickness of the implant, and laxity inthe joint. Input 610 can be used to select a total thickness of anatural knee. Alternatively, input 610 can be used to select a totalthickness of an implant, total or partial, for comparison. Thus, input612 can be used to select as in input or view as an output hypotheticalthickness of bone to be removed and an amount of space remaining. Inexamples, input 610 and input 612 can be fixed to the natural knee jointor can be eliminated from the interface. As such, inputs 602-612 arediscussed with reference to the medial side of the knee joint beingconsidered and planned for replacement. However, inputs 602-612 canadditionally be used for considering and planning the lateral side ofthe knee joint for replacement. Thus, user interface 600 can includecomponents for separately planning a partial knee arthroplasty on alateral side or a medial side of the joint, or a total kneearthroplasty. Input 602 can be changed to indicate a position of theknee for extension such that the amount of bone to be removed from thedistal end of the femur can be planned. Thus, using user interface 600to determine how much of the distal end of the bone is to be removed andhow much of the posterior side of the bone is to be removed, a surgeoncan obtain an indication of how much laxity will be in the joint afterthe knee implant is implanted. The surgeon can then vary the amount ofthe distal resection and posterior resection to obtain desirable laxityand the surgeon can see how varying one parameter affects otherparameters to thereby plan a properly placed and fit prosthetic device.The surgeon can select any of the inputs or outputs to be fixed, such asposterior cut, distal cut, any of the device thicknesses, etc., whileadjusting other settings to see how one selection affects the others.User interface 600 can be used in conjunction with any of the proceduresdescribed herein to pre-operatively plan a surgical procedure that canbe used to direct the procedure and intraoperatively adapt theprocedure, such as by using the method described with reference to FIG.3D.

FIG. 7 illustrates system 700 for performing techniques describedherein, in accordance with some embodiments. System 700 is an example ofa system that can incorporate surgical system 100 of FIG. 1 . System 700can include robotic surgical device 702 (e.g., robotic system 115)coupled to resection guide instrument 704 (e.g., resection guideinstrument 200 of FIG. 2 ), which may interact with tracking system 706.In other examples, the resection guide instruments described herein canbe used without tracking system 706. Tracking system 706 can includetracking element 708, camera 710 and registration device 711 (e.g.,pointer 326). Resection guide instrument 704 (e.g., instrument 200) caninclude attachment instruments 712 (e.g., posterior resection guides300, 430 and 500). System 700 can include display device 714, which canbe used to display user interface 716. System 700 can include controlsystem 718 (e.g., a robotic controller or computing system 140 of FIG. 1), including processor 720 and memory 722. In an example, display device714 can be coupled to one or more of robotic surgical device 702,tracking system 706, or control system 718. As such, data generated byregistration device 711 can be shared with control system 718, trackingsystem 706 and an operator of system 700 via display device 714. Inexamples, guide instrument 704 can be operated without input fromtracking system 700, after a registration process, such that roboticsurgical device 702 can be positioned and tracked by movement of roboticarm 120 within the native coordinate system of robotic arm 120. Once ina desired position, resection guide instruments 704 and attachmentinstruments 712 can be freely used by a surgeon without tracking system706 required to reacquire position information for robotic surgicaldevice and without control system 718 losing track of the location ofrobotic surgical device 702.

FIG. 8 illustrates a block diagram of an example machine 1700 upon whichany one or more of the techniques discussed herein may be performed inaccordance with some embodiments. For example, machine 1700 can comprisecomputing system 140 of FIG. 1 . Machine 1700 can comprise an example ofa controller for robotic system 115 and sensors 1721 can includetracking element 170 and tracking device 332. As such instructions 1724can be executed by processor 1702 to generate and correlate position andorientation information to determine the position and orientation of asurgical instrument relative to robotic arm 120. For example, positionand geometric information of partial knee resection guide 400 andpartial knee resection guide 502 via connection to robotic arm 120relating to the location of resection block 406 and adapter block 518relative to extension arm 404 and extension arm 516 can be stored inmain memory 1704 or static memory 1706 and accessed by processor 1702.Additionally, the shapes and geometric information, such as thicknesses,for gap checker 802, gap checker 860, posterior resection guide 300,posterior resection guide 430 of FIG. 4D and posterior resection guide500 of FIG. 5A can be stored in memory 1704 and accessed by processor1702. Processor 1702 can also receive input (such as at input device1712) relating to the position of tibia T and pointer 326 relative torobotic arm 120 via tracking element 170 and tracking device 332, whichcan be stored in main memory 1704. Processor 1702 can further relateposition information of posterior resection guide 430 and posteriorresection guide 500 to the position information of robotic arm 120through partial knee resection guide 400 and partial knee resectionguide 502 to correlate the position of resection block 406 and adapterblock 518 to the coordinate system of surgical system 100, such as bybeing programmed with the shapes, geometries and dimensions thereof. Assuch, as resection block 406 and adapter block 518, and posteriorresection guide 430 and posterior resection guide 500, when attachedthereto, moves, machine 1700 can continuously track and update thelocation of said components relative to robotic arm 120 via movement ofrobotic arm 120 and, for example, display said position on display unit1710 (e.g., human interface devices 145), as well as the location offeatures included thereon, such as cutting guide features.

In alternative embodiments, machine 1700 may operate as a standalonedevice or may be connected (e.g., networked) to other machines. In anetworked deployment, machine 1700 may operate in the capacity of aserver machine, a client machine, or both in server-client networkenvironments. In an example, machine 1700 may act as a peer machine inpeer-to-peer (P2P) (or other distributed) network environment. Machine1700 may be a personal computer (PC), a tablet PC, a set-top box (STB),a personal digital assistant (PDA), a mobile telephone, a web appliance,a network router, switch or bridge, or any machine capable of executinginstructions (sequential or otherwise) that specify actions to be takenby that machine. Further, while only a single machine is illustrated,the term “machine” shall also be taken to include any collection ofmachines that individually or jointly execute a set (or multiple sets)of instructions to perform any one or more of the methodologiesdiscussed herein, such as cloud computing, software as a service (SaaS),other computer cluster configurations.

Machine (e.g., computer system) 1700 may include hardware processor 1702(e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), mainmemory 1704 and static memory 1706, some or all of which may communicatewith each other via interlink (e.g., bus) 1708. Machine 1700 may furtherinclude display unit 1710, alphanumeric input device 1712 (e.g., akeyboard), and user interface (UI) navigation device 1714 (e.g., amouse). In an example, display unit 1710, input device 1712 and UInavigation device 1714 may be a touch screen display. Machine 1700 mayadditionally include storage device (e.g., drive unit) 1716, signalgeneration device 1718 (e.g., a speaker), network interface device 1720,and one or more sensors 1721, such as a global positioning system (GPS)sensor, compass, accelerometer, or other sensor. Machine 1700 mayinclude output controller 1728, such as a serial (e.g., Universal SerialBus (USB), parallel, or other wired or wireless (e.g., infrared (IR),near field communication (NFC), etc.) connection to communicate orcontrol one or more peripheral devices (e.g., a printer, card reader,etc.).

Storage device 1716 may include machine readable medium 1722 on which isstored one or more sets of data structures or instructions 1724 (e.g.,software) embodying or utilized by any one or more of the techniques,operations or functions described herein, such as those utilized tocarry out the methods described with reference to FIG. 13 and elsewhere.Instructions 1724 may also reside, completely or at least partially,within main memory 1704, within static memory 1706, or within hardwareprocessor 1702 during execution thereof by machine 1700. In an example,one or any combination of hardware processor 1702, main memory 1704,static memory 1706, or storage device 1716 may constitute machinereadable media.

While machine readable medium 1722 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 1724. The term “machine readable medium” may include anymedium that is capable of storing, encoding, or carrying instructionsfor execution by machine 1700 and that cause machine 1700 to perform anyone or more of the techniques of the present disclosure, or that iscapable of storing, encoding or carrying data structures used by orassociated with such instructions. Non-limiting machine readable mediumexamples may include solid-state memories, and optical and magneticmedia.

Instructions 1724 may further be transmitted or received overcommunications network 1726 using a transmission medium via networkinterface device 1720 utilizing any one of a number of transferprotocols (e.g., frame relay, internet protocol (IP), transmissioncontrol protocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards,peer-to-peer (P2P) networks, among others. In an example, networkinterface device 1720 may include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tocommunications network 1726. In an example, network interface device1720 may include a plurality of antennas to wirelessly communicate usingat least one of single-input multiple-output (SIMO), multiple-inputmultiple-output (MIMO), or multiple-input single-output (MISO)techniques. The term “transmission medium” shall be taken to include anyintangible medium that is capable of storing, encoding or carryinginstructions for execution by machine 1700, and includes digital oranalog communications signals or other intangible medium to facilitatecommunication of such software.

The systems, devices and methods discussed in the present applicationcan be useful in performing robotic-assisted surgical procedures thatutilize robotic surgical arms that can be used to position devicesrelative to a patient to perform arthroplasty procedures, such aspartial knee arthroplasties. In particular the systems, devices andmethods disclosed herein are useful in improving the accuracy with whichposterior cuts and other finishing cuts on a femur are performed. Thesystems, devices and methods disclosed herein can reduce or eliminatethe need for reliance on manually positioning of cutting guides byutilizing surgical guidance systems to orient finishing guides eitherdirectly with navigation or through positioning with a robotic surgicalarm.

FIG. 9 is a perspective view of a knee joint 800 having gap checker 802inserted between proximal resection 804 of tibia T connected to firsttracker 806 and posterior portion 808 of a femur F connected to secondtracker 810. Femur F can include diaphysis region 812 to which secondtracker 810 can be attached and epiphysis region including condyles 814Aand 814B. The distal portion of condyle 814B can be resected to formresected surface 816. Tibia T can include diaphysis region 818 to whichfirst tracker 806 can be attached and epiphysis region 820 includingresected tibial plateau 822. Resected tibial plateau 822 can be resectedto form proximal a vertical surface adjacent to proximal resection 804and opposite condyle 814B. First tracker 806 and second tracker 810 canbe configured similarly to pointer 326 pointer tracker device 332 (FIG.3B). For example, first tracker 806 can comprise pointer 840 and trackerdevice 842 and second tracker 810 can comprise pointer 844 and trackerdevice 846.

When knee joint 800 is positioned in extension, proximal resection 804can face resected surface 816. In order for femur F to receive auni-condylar implant, posterior portion 808 of condyle 814B is typicallyresected. As discussed herein, the thickness of the resection ofposterior portion 808 of condyle 814B can be determined by placing kneejoint 800 in flexion where proximal resection 804 faces posteriorportion 808. The amount of bone matter to be removed can be determinedbased on, for example, surgeon skill and experience in determining jointtension or laxity, such as controlled by tension or laxity in medialcollateral ligament (MCL) 824 and other ligaments. To facilitatedetermination of how much of a resection to take off of posteriorportion 808, gap checker 802 can be inserted between proximal resection804 and posterior portion 808. In this orientation, feature 826 canrepresent the thickness of the planned tibial component thickness, orpossibly represent a simple measurement of the flexion gap. Gap checker802 can comprise one or more blocks, or gap gauges, having opposingsurfaces configured to engage proximal resection 804 and posteriorportion 808 of condyle 814B. In examples, the opposing surfaces can beparallel. In the illustrated example, gap checker 802 comprises block826 and block 828. Block 826 can have sidewall 830 and block 828 canhave sidewall 832. Sidewall 830 can have a first thickness betweenopposing parallel surfaces and sidewall 832 can have a second thicknessbetween opposing parallel surfaces. In particular, block 826 can includeupper surface 834 and block 828 can include upper surface 836. Sidewall832 can be thicker than sidewall 830, as illustrated in FIG. 9 . Uppersurface 834 and upper surface 836 can provide offset from proximalresection 804 that can be used to set or determine the position forposterior resection guide 430 of FIGS. 4C and 4D and posterior resectionguide 500 of FIG. 5A. Additionally, upper surface 834 and upper surface836 can comprise reference features for the positioning of a cut guide,e.g., posterior resection guide 430 of FIGS. 4C and 4D and posteriorresection guide 500 of FIG. 5A, as discussed below.

A surgeon can manually position femur F relative to tibia T to determinea gap height between proximal resection 804 and posterior-most point 838for performing a posterior resection of condyle 814B. The gap height canbe digitized using pointer 840 and pointer 844. Pointer 840 can beengaged with tibia T, such as by pushing a pointed tip into corticalbone matter. Pointer 844 can be engaged with femur F, such as by pushinga pointed tip into cortical bone matter. Thus, tracker device 842 andtracker device 846 can be used to track the locations on the bones wherepointers 840 and 844 are engaged. For example, pointers 840 and 844 canbe inserted into landmarks, such as boney features, determined fromthree-dimensional digital models of tibia T and femur F, in order tocalibrate the location of tibia T and femur F with the three-dimensionalspace of surgical area 105. Tracker devices 842 and 846 can be used tosend or otherwise communicate real-time positional information tocomputing system 140 (FIG. 1 ). Block 826 or block 828 of gap checker802 can be inserted into the gap between proximal resection 804 andposterior portion 808 of condyle 814B. Once the proper positioning offemur F and tibia T and a gap checker 802 having a desired thickness toset the desired tension of knee joint 800 or MCL 824, the surgeon or asurgical technician can record the positions of femur F and tibia Tusing computing system 140 (FIG. 1 ). The location of posterior-mostpoint 838 on condyle 814B and proximal resection 804 can be known tocomputing system 140 due to, for example, inclusion of three-dimensionalcoordinates for bone models of femur F and tibia T. As such, the gapheight between posterior-most point 838 and proximal resection 804produced by block 826 can be determined by computing system 140 anddigitized to prepare three-dimensional coordinates for the placement ofa posterior resection guide. Gap checker 802 can be used to hold theposition of femur F and tibia T set by the surgeon to facilitateaccurate digitization. The shape of gap checker 802 need not be known tocomputing system 140. However, as explained with reference to FIG. 11 ,the geometry of gap checker devices can be stored in memory of computingsystem 140. After digitizing the gap height, computing system 140 canthen compute the location for the resection of condyle 814B aboveproximal resection 804. For example, computing system 140 can calculatethe location above posterior-most point 838 where the posterior-mostsurface of a prosthetic condyle implant would be located in order forthe prosthetic condyle implant and prosthetic tibial component to occupythe same amount of space as gap checker 802 and the bone to be removed,e.g., to replicate the same amount of tension in knee joint 800 or MCL824 as is being produced with gap checker 802. Thus, computing system140 can calculate the location for virtual cut plane 848 in thethree-dimensional space of surgical area 105 relative to tibia T andfemur F. Virtual cut plane 848 can comprise a plane parallel to proximalresection 804 that is spaced from a parallel plane that is tangent toposterior-most point 838 an amount equal to the height of block 826 forthe example of FIG. 9 . In other words, the plane of upper surface 834can be digitized as a reference for placement of a posterior resectionguide. Thus, robotic arm 120 (FIG. 1 ) can position posterior cut guidesurface 434 of posterior resection guide 430 (FIG. 4C) or resectionblock 506 of posterior resection guide 500 (FIG. 5A) at a location toalign a cut guide surface with virtual cut plane 848 to facilitateremoval of a posterior portion of condyle 814B using an appropriatecutting instrument guided along posterior cut guide surface 434 orresection block 506. In examples, the plane of upper surface 834 cancomprise a plane where a bottom surface of posterior resection guide 430or posterior resection guide 500 can be positioned to perform thedesired resection at virtual cut plane 848. Thus, FIG. 9 illustrates amethod for positioning a posterior resection guide in athree-dimensional coordinate system using a robotic arm to perform apartial knee arthroplasty wherein a gap checker can be used toimmobilize a knee joint gap height to allow digitization of a resectionplane through known coordinates of tibia T and femur F. In additionalexamples, the digitization of a reference location for the resectionplane can be recorded directly from gap checker 802.

FIG. 10 is a perspective view of knee joint 800 having gap checker 802inserted between proximal resection 804 of tibia T and posterior portion808 of femur F and third tracker 850 engaged with upper surface 834 ofgap checker 802. Third tracker 850 can comprise pointer 852 and trackerdevice 854. Third tracker 850 can be used to collect digital points ongap checker 802 for instructing computing system 140 where to positionposterior resection guide 430 of FIGS. 4C and 4D and posterior resectionguide 500 of FIG. 5A. Upper surface 834 and upper surface 836 cancomprise reference features for the positioning of a cut guide, e.g.,posterior resection guide 430 of FIGS. 4C and 4D and posterior resectionguide 500 of FIG. 5A. In examples, upper surfaces 834 and 836 cancomprise reference features for the engagement of bottom surfaces ofposterior resection guides 430 and 500.

The configuration of FIG. 10 can be used to determine the location forvirtual cut plane 848. Input from third tracker 850 can be used tosupplement or fine tune information collected from first tracker 806 andsecond tracker 810 to determine the location of virtual cut plane 848.Alternatively, input from third tracker 850 can be used as analternative to information collected from first tracker 806 and secondtracker 810 to determine the location of virtual cut plane 848. Thus, inexamples, first tracker 806 and second tracker 810 can be omitted fromdetermining the location for virtual cut plane 848, but can be connectedto tibia T and femur F for other purposes in performing a partial kneearthroplasty.

As illustrated in FIG. 10 , third tracker 850 can be used to digitallymark the location of upper surface 834. Tip of pointer 852 can betouched to upper surface 834, such as by being drawn across or tapped onupper surface 834, to collect multiple points that can be connected bycomputing system 140 to form a plane. The plane of collected points canbe a plane where a bottom surface of posterior resection guide 430 orposterior resection guide 500 can be positioned to perform the desiredresection at virtual cut plane 848. Computing system 140 (FIG. 1 ) cancalculate the location of virtual cut plane 848 from upper surface 834as explained above. Thus, third tracker 850 can be used to directlydetermine the location of upper surface 834 rather than having tocalculate the equivalent location of upper surface 834 through thecoordinates of the digital models of tibia T and femur F as can be doneusing first tracker 806 and second tracker 810 only.

In additional examples, third tracker 850 can be used to mark locationson resected surface 816 directly that can be used as landmarks for thepositioning of posterior resection guides 430 and 500. For example,third tracker 850 can be used to directly draw or mark virtual cut plane848 on resected surface 816.

Thus, FIG. 10 illustrates a method for positioning a posterior resectionguide in a three-dimensional coordinate system using a robotic arm toperform a partial knee arthroplasty wherein a gap checker can be used toimmobilize a knee joint gap height to allow digitization of a resectionplane through coordinates from a surface of the gap checker.

FIG. 11 is a perspective view of knee joint 800 having gap checker 860inserted between proximal resection 804 of tibia T and posterior portion808 of femur F and tracking device 862 connected to gap checker 860. Inexamples, gap checker 860 can be configured similarly to devicesdescribed in Pub. No. US 2022/0183701 to Gogarty et al., the contents ofwhich are hereby incorporated herein by this reference. Gap checker 860can comprise block 864 and coupler 866. Block 864 can comprise uppersurface 868 and sidewall 870. Gap checker 860 can be connected totracking device 862, which can comprise pointer 872 and tracker device874. In particular, pointer 872 can be inserted into socket 876 withincoupler 866 and fastened thereto via set screw 878. Pointer 872 caninclude an orientation mechanism (e.g., detent, keying surface) toensure that pointer 872 and block 864 are attached in a reliable andprecise configuration. In examples, pointer 872 can include a threadedaperture at socket 876 and pointer 872 can include a threaded tip. Assuch, the relative location between tracker device 874 and block 864 canbe fixed in a known relationship that can be stored in memory 1704 ofcomputing system 140. Block 864 can be configured similarly to block 826or block 828 of gap checker 802 of FIGS. 9 and 10 . In examples, aplurality of gap checker 860 can be provided and used by a surgeonduring a partial knee arthroplasty, with each instance of gap checker860 having a different thickness of block 864. As such, a surgeon caninsert different sized gap checkers 860 between femur F and tibia Tuntil the desired tension in MCL 824 is obtained. The shapes of thevarious thicknesses of gap checker 860 can be stored in memory ofcomputing system 140. The location of the shape of gap checker 860 canbe determined using tracker device 874, including the location of uppersurface 868. The plane of upper surface 868 can be a plane where abottom surface of posterior resection guide 430 or posterior resectionguide 500 can be positioned to perform the desired resection at virtualcut plane 848. Computing system 140 (FIG. 1 ) can calculate the locationof virtual cut plane 848 from upper surface 868 as explained above.Thus, tracker device 874 can be used to directly determine the locationof upper surface 868 without having to manually collect digital pointsalong upper surface 868 using a separate handheld tracker device.

Thus, FIG. 11 illustrates a method for positioning a posterior resectionguide in a three-dimensional coordinate system using a robotic arm toperform a partial knee arthroplasty wherein a gap checker can be used toimmobilize a knee joint gap height to allow digitization of a resectionplane through coordinates from a surface of the gap checker.

FIG. 12 is a perspective view of a knee joint 360 havingmanually-positioned posterior resection guide 300 inserted betweenproximal resected surface 320 of tibia T and posterior portion 362 offemur F. Posterior resection guide 300 can be configured as describedwith reference to FIGS. 3A and 3B. However, rather than posteriorresection guide 300 being connected to handle 302 (FIG. 3A), posteriorresection guide 300 can be connected to tracker device 370. Trackerdevice 370 can comprise coupler 372 and tracker element 374. Posteriorresection guide 300 can be placed against resected surface 318 such thatflange 306 enters the gap between posterior portion 362 and proximalresected surface 320. A surgeon can move the position of posteriorresection guide 300 against resected surface 318 to achieve the desiredgap height. As discussed above, shims can be positioned above or belowflange 306 to facilitate positioning and holding of posterior resectionguide 300 in position. As discussed above, tracker device 370 can beused to track the position of posterior resection guide 300 in real-timeon a display screen of computing system 140 to move tip 324 to thelocation of point 350 (FIG. 3D) on the display screen to positionposterior resection guide 300 is a desired location. Tracker device 370can be used to digitize a location for posterior resection guide 300 todetermine a location for placement of posterior resection guide 430,which can have the same functional shape as posterior resection guide300 except for flange 306 and the coupling to tracker device 370 orresection block 406.

FIG. 13 is a block diagram of examples of methods 900 for obtainingcoordinates for and positioning a posterior resection guide for apartial knee arthroplasty. Method 900 can comprise operation 902 throughoperation 930 that describe various procedures for performing a partialposterior resection of a femur. In various examples, additionaloperations consistent with the systems, methods and operations describedherein can be included, and some of operation 902 through operation 930can be omitted. Furthermore, operation 902—operation 930 can beperformed in different orders than the illustrated example.

At operation 902, tracking devices can be attached to tibia T and femurF. For example, first tracker 806 can be attached to tibia T and secondtracker 810 can be attached to femur F.

At operation 904, tibia T and femur F can be positioned relative to eachother for performing a posterior resection of femur F. For example, kneejoint 800 can be put into flexion after proximal resection 804 of tibiaT has been performed. As such, the gap between condyle 814B and proximalresection 804 can be accessed by a surgeon.

At operation 906, the gap height between posterior-most point 838 andproximal resection 804 can be adjusted. For example, a surgeon canadjust the gap height to provide knee joint 800 with desirable laxity,e.g., laxity that reproduces the feel of a natural knee joint. A surgeoncan rely on experience and intraoperative observation of knee joint 800to determine the desired laxity. In examples, the surgeon can set thelaxity, e.g., gap height, of knee joint 800 free-hand without the use ofother instruments or gap checkers. In examples, a surgeon can utilizeone or both of posterior resection guide 300 and a gap checker, such asgap checker 802 of FIGS. 9 and 10 or gap checker 860 of FIG. 11 , toadjust the gap height.

At operation 908, a surgeon can position posterior resection guide 300in relationship to femur F. For example, body 304 can be positionedagainst resected surface 816 and flange 306 can be positioned in thegap. In examples, posterior resection guide 300 can be positioned on topof other devices, such as shims 342 (FIG. 3D) or gap checker 802 (FIG. 9), to adjust the gap height. In examples, flange 306, shims and gapcheckers can be used to hold the gap height at a fixed distance to allowfor digitization.

At operation 910, a reference feature of posterior resection guide 300can be digitized. That is, a surgeon can position posterior resectionguide 300 against distal resected surface 816 in a location where theposterior cut is to be performed. The digitized reference feature can besubsequently converted into three-dimensional coordinate information insurgical area 105 for robotic arm 120 to position posterior resectionguide 430 of FIG. 4D or posterior resection guide 500 of FIG. 5A.

At operation 912, pointer 326 of FIGS. 3B and 3C can be engaged withposterior resection guide 300. Pointer 326 can be traced along a featureof posterior resection guide 300. In examples, pointer 326 can be tracedalong tip 324 of the anterior flange, as discussed with reference toFIG. 3B. In examples, pointer 326 can trace along cut guide surface 308.

At operation 914, tracker device 370 can be coupled to posteriorresection guide 300, such as is shown in FIG. 12 . Tracker device 370can be attached to posterior resection guide 300 in a fixed manner suchthat the entire geometry or just specific reference features ofposterior resection guide 300, such as tip 324 or cut guide surface 308,can be known to computing system 140.

As an alternative to operations 908-914, some or all of operations916-924 can be performed.

At operation 916, a gap checker can be inserted into the space betweenposterior-most point 838 and proximal resection 804. For example, gapchecker 802 of FIGS. 9 and 10 can be used or gap checker 860 of FIG. 11can be used. The gap checkers can be used to hold the gap height at afixed distance to allow for digitization.

At operation 918, gap checker 802 can be inserted between posterior-mostpoint 838 and proximal resection 804. Blocks 826 and 828 can be insertedtherein to test the laxity of knee joint 800 for different thicknesses.After a surgeon has positioned a block of a gap checker having thedesired thickness into the gap, the pose of tibia T and femur F can becaptured using tracker device 842 and tracker device 846. As describedherein, tracker devices 842 and 846 can be used to determine theposition between tibia T and femur F including the gap height betweenposterior-most point 838 and proximal resection 804. Computing system140 can utilize the recorded gap height produced by the gap checkerinserted in the gap to determine a location for posterior resectionguide 430 of FIG. 4D or posterior resection guide 500 of FIG. 5A toperform a posterior resection that will reproduce the set gap heightafter prosthetic components are implanted.

At operation 920, a feature of a gap checker can be digitized orrecorded to provide a reference location for computing system 140 toposition posterior resection guide 430 of FIG. 4D or posterior resectionguide 500 of FIG. 5A.

At operation 922, tracked gap checker 860 of FIG. 11 can be used. Theentire geometry of tracked gap checker 860 can be known to computingsystem 140 due to the correlation of gap checker 860 and tracking device862.

At operation 924, gap checker 802 of FIG. 10 can be used in conjunctionwith third tracker 850. Third tracker 850 can be used to record specificfeatures of gap checker 802 for digitization by computing system 140.

At operation 926, the reference positions and features captured atoperations 910-924 can be digitized for computing system 140 and roboticsystem 115. As discussed herein, the digitized surfaces and features canbe used to record a location in the 3D space of surgical area 105 forthe placement of posterior resection guide 430 of FIG. 4D or posteriorresection guide 500 of FIG. 5A relative to tibia T and femur F withrobotic arm 120.

At operation 928, the captured reference positions and features ofoperation 926 can be converted to instructions for the positioning ofposterior resection guide 430 of FIG. 4D or posterior resection guide500 of FIG. 5A. Computing system 140 can convert the digitized referenceposition or features to the desired position of cut guide surface 434 orresection block 506 by extrapolating the location of cut guide surface434 or resection block 506 from the geometry of instruments they areattached to, such as resection guide 400 and resection guide 500.

At operation 929, a surgeon can perform final checks and adjustment ofthe positioning of the femur and tibia relative to each other.Digitizing aspects of gap checker 802, such as upper surface 834, andfeatures of resection guide 300, such as anterior tip 324, as describedwith reference to FIGS. 9-12 are important for determining and freezingor locking the relative tibial-femoral orientation in athree-dimensional coordinate system. Such orientation can result whenthe MCL is appropriately tensed to reflect the final implanted state.The surgeon can additionally fine-tune other aspects of the placement ofthe femoral cut guide per direct observation and surgeon preference. Forexample, the surgeon can adjust the size of the femoral implant, theinterior-exterior rotation of the cut guide, the medial-lateral positionof the cut guide, as well as other parameters. In examples, suchsurgeon-implemented adjustments do not adjust the positioning betweenthe femur and tibia determined in the preceding steps or operations, butcan provide adjustment of the femoral bone cut plane within the gapenvelope determined by the position between the femur and tibia. Suchsurgeon-implemented adjustments can be used to address componentperipheral fit on the cut, appropriate rotation to the patella, abilityto centralize the ninety-degree contact part of the femur over thecenter of the tibia, as well as other parameters.

At operation 930, robotic arm 120 can move posterior resection guide 430of FIG. 4D or posterior resection guide 500 of FIG. 5A to the instructedlocation against femur F to perform the posterior resection. Robotic arm120 can move posterior resection guide 430 of FIG. 4D or posteriorresection guide 500 of FIG. 5A to the desired location without a surgeonhaving to hold a manual cut guide in place. A surgeon can guide acutting blade of a cutting instrument against or along posterior cutguide surface 434 or resection block 506.

EXAMPLES

Example 1 can include or use subject matter such as a method foraligning a posterior resection guide with a distal femur surface thatcan comprise positioning a posterior resection guide adjacent a proximalresected surface of a tibia and a posterior surface of a femur for aknee joint in flexion, displaying a representation of a distal end ofthe femur on graphical display, displaying an alignment axis on therepresentation, engaging a tracking device to the posterior resectionguide, tracking an anterior tip of the posterior resection guide on agraphical display, and rotating the posterior resection guide to alignthe anterior tip with the alignment axis on the graphical display.

Example 2 can include, or can optionally be combined with the subjectmatter of Example 1, to optionally include an performing a posteriorresection of the femur using a guide surface on the posterior resectionguide.

Example 3 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 or 2 to optionallyinclude generating the alignment axis by aligning a center of a tibiaplateau with a femoral condyle with the knee joint in extension, markingthe distal end of the femur with a distal indicator, rotating the kneejoint into flexion to project the center of the tibia plateau onto aposterior side of the femoral condyle, marking a posterior surface ofthe femur with a posterior indicator, and projecting an axis from theposterior indicator, through the distal indicator to a location on ananterior side of the femur.

Example 4 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 through 3 to optionallyinclude a engaging the tracking device to the posterior resection guideby attaching the tracking device to an instrument, and engaging ageometric feature of the instrument with the anterior tip of theposterior resection guide.

Example 5 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 through 4 to optionallyinclude enaging the tracking device to the posterior resection guide bymounting the tracking device to the posterior resection guide.

Example 6 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 through 5 to optionallyinclude positioning the posterior resection guide adjacent the proximalresected surface of the tibia and the posterior surface of the femur byinserting a flange projecting from the posterior resection guide betweenthe proximal resected surface and the posterior surface such that theposterior resection guide engages the distal femur surface.

Example 7 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 through 6 to optionallyinclude a posterior resection guide that is manually positioned adjacentthe distal femur surface and a posterior resection guide that ismanually rotated to align the anterior tip with the alignment axis onthe graphical display.

Example 8 can include or use subject matter such as a system forperforming femoral resections for a partial knee arthroplasty that cancomprise a surgical robot comprising an articulating arm configured tomove within a coordinate system for the surgical robot, a femoralresection guide instrument comprising a coupler for connecting to thearticulating arm, an extension arm extending from the coupler, and aresection block attached to the extension arm, and a finishing guide forperforming a posterior resection of a distal femur, wherein thefinishing guide is positionable by the surgical robot to determine athickness and rotation of the posterior cut.

Example 9 can include, or can optionally be combined with the subjectmatter of Example 8, to optionally include a resection block that cancomprise a cutting guide surface, and a plurality of pin bores.

Example 10 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 8 or 9 to optionallyinclude a finishing guide that is positionable by the surgical robot viaplacement of pin holes with the resection block.

Example 11 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 8 through 10 to optionallyinclude a finishing guide that can include a flange having a pluralityof bores arranged in a pattern that align with a pattern of theplurality of bores of the resection block.

Example 12 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 8 through 11 to optionallyinclude a finishing guide that is positionable by the surgical robot viaengagement with the resection block.

Example 13 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 8 through 12 to optionallyinclude a finishing guide that can comprise a coupling flange configuredto engage a slot formed by the cutting guide surface or one or morebores of the plurality of pin bores.

Example 14 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 8 through 13 to optionallyinclude a controller for the surgical robot that can comprise anon-transitory storage medium having computer-readable instructionsstored therein comprising dimensional data for the femoral resectionguide instrument, dimensional data for the finishing guide, andinstructions for moving an end of the articulating arm to position thefinishing guide into specific locations within the coordinate systemaccording to a surgical plan.

Example 15 can include or use subject matter such as a method forresecting a distal femur for a partial knee arthroplasty that cancomprise attaching a resection guide instrument to an articulating armof a robotic surgical system, moving the resection guide instrument toan anterior or posterior side of a distal end of a femur, resecting thedistal end of the femur to form a distal resection surface, moving theresection guide instrument to the distal resection surface, drillingholes into the distal resection surface through the guide bores in theresection guide instrument, inserting pins into the drilled holes,attaching a finishing guide to the inserted pins, and resecting aposterior side of the femur adjacent the distal resection surface usingthe finishing guide to guide a cutting instrument.

Example 16 can include, or can optionally be combined with the subjectmatter of Example 15, to optionally include moving the resection guideinstrument to a proximal end of a tibial, and resecting the proximal endof the tibia to form a proximal resection surface.

Example 17 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 15 or 16 to optionallyinclude resecting a chamfer cut on the femur adjacent the distalresection surface and the resected posterior side of the femur using achamfer guide surface of the finishing guide.

Example 18 can include or use subject matter such as a method foraligning a posterior resection guide with a distal resected femursurface that can comprise positioning a posterior resection guideadjacent the distal resected femur surface, inserting a flange of theposterior resection guide between a posterior surface of a femur and aproximal resected surface of a tibia, moving the posterior resectionguide medial-laterally to observe a rim thickness between an anterioredge of the posterior resection guide relative to an edge of the distalresected femur surface, and positioning shims adjacent the flange tovary the rim thickness.

Example 19 can include or use subject matter such as a system forperforming femoral resections for a partial knee arthroplasty that cancomprise a surgical robot comprising an articulating arm configured tomove within a coordinate system for the surgical robot, a trackingsystem configured determine locations of one or more trackers in thecoordinate system, a tracker configured to be tracked by the trackingsystem, a finishing guide configured to be coupled to the articulatingarm to perform a posterior resection of a distal femur, a controller forthe surgical robot that can comprise a communication device configuredto receive data from and transmit data to the surgical robot and thetracking system, a display device for outputting visual information fromthe surgical robot and the tracking system, and a non-transitory storagemedium having computer-readable instructions stored therein comprisingmarking digital locations at a distal end and a posterior surface of adistal end of a femur using the tracker, displaying the digitallocations of the distal end and posterior surface on the display device,plotting a target axis extending through the distal end and theposterior surface on the display device, projecting the target axis toan anterior surface of the femur, and moving the articulating arm toalign the finishing guide along the target axis at the anterior surface.

Example 20 can include, or can optionally be combined with the subjectmatter of Example 19, to optionally include a femoral resection guideinstrument that can comprise a coupler for connecting to thearticulating arm, an extension arm extending from the coupler, and aresection block attached to the extension arm.

Example 21 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 19 or 20 to optionallyinclude a finishing guide that can be coupled to the resection block sothat the articulating arm can position the finishing guide along thetarget axis.

Example 22 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 19 through 21 to optionallyinclude a resection guide that can further comprise a first plurality ofpin holes and a finishing guide that can further comprise a secondplurality of pin holes, wherein the articulating arm can position thefirst plurality of pin holes so that bores can be drilled to receivepins that receive the second plurality of pin bores.

Example 23 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 19 through 22 to optionallyinclude a non-transitory storage medium that has computer-readableinstructions stored therein further comprising dimensional data for thefemoral resection guide instrument, dimensional data for the finishingguide, and instructions for moving an end of the articulating arm toposition the finishing guide into specific locations within thecoordinate system according to a surgical plan.

Example 24 is a method of positioning a posterior resection guide in athree-dimensional coordinate system using a robotic arm in order toperform a partial knee arthroplasty, the method comprising: connecting afirst tracking device for a surgical tracking system of the robotic armto a femur; connecting a second tracking device for the surgicaltracking system of the robotic arm to a tibia; manually positioning thetibia relative to the femur to a desired orientation to perform aposterior resection; manually determining a position for the posteriorresection guide to perform the posterior resection; digitizing areference point for the posterior resection guide in thethree-dimensional coordinate system for a location of a feature of theposterior resection guide; moving the posterior resection guide to thelocation in the three-dimensional coordinate system with the roboticarm; and resecting a posterior portion of a condyle of the femur usingthe posterior resection guide to guide a cutting instrument.

In Example 25, the subject matter of Example 24 optionally includeswherein the reference point for the posterior resection guide in thethree-dimensional coordinate system for the location of the posteriorresection guide comprises a digital reference location for the featureof the posterior resection guide on a distal end of the femur.

In Example 26, the subject matter of Example 25 optionally includeswherein the feature comprises an anterior tip of the posterior resectionguide.

In Example 27, the subject matter of Example 26 optionally includeswherein marking the digital reference location comprises engaging atracked-pointer device with a location on an anterior side of thecondyle to be resected.

In Example 28, the subject matter of Example 27 optionally includeswherein engaging the tracked-pointer device with the location on theanterior side of the condyle to be resected comprises: marking a firstlocation at a distal location of the condyle in extension; and marking asecond location at a posterior location on the condyle in flexion; anddrawing a line through the first and second locations to the location onthe anterior side of the condyle.

In Example 29, the subject matter of any one or more of Examples 26-28optionally include wherein marking the digital reference locationcomprises engaging a third tracking device with an analogous feature ofa manually positioned posterior resection guide for the feature.

In Example 30, the subject matter of any one or more of Examples 26-29optionally include wherein marking the digital reference locationcomprises utilizing a third tracking device coupled to a manuallypositioned posterior resection guide.

In Example 31, the subject matter of any one or more of Examples 26-30optionally include wherein marking the digital reference locationcomprises marking a location of a resection guide surface on a manuallypositioned posterior resection guide.

In Example 32, the subject matter of any one or more of Examples 25-31optionally include resecting a distal portion of the femur afterdigitizing the reference point for the posterior resection guide in thethree-dimensional coordinate system for the location of the posteriorresection guide.

In Example 33, the subject matter of any one or more of Examples 24-32optionally include wherein the reference point for the posteriorresection guide in the three-dimensional coordinate system for thelocation of the posterior resection guide comprises a digital referencelocation for the feature of the posterior resection guide relative to aproximal surface of the tibia.

In Example 34, the subject matter of Example 33 optionally includesresecting a proximal portion of the tibia before digitizing thereference point for the posterior resection guide in thethree-dimensional coordinate system for the location of the posteriorresection guide.

In Example 35, the subject matter of any one or more of Examples 33-34optionally include wherein the feature comprises a distal surface of theposterior resection guide.

In Example 36, the subject matter of Example 35 optionally includeswherein digitizing the reference point for the posterior resection guidein the three-dimensional coordinate system for the location of theposterior resection guide comprises: digitizing a distance between aproximal resection surface of the tibia and an unresected posteriorcondyle of the femur.

In Example 37, the subject matter of Example 36 optionally includeswherein manually positioning the tibia to the femur comprises insertinga gap control device between a proximal portion of the tibia and aposterior portion of the femur.

In Example 38, the subject matter of Example 37 optionally includeswherein marking the digital reference location comprises engaging atracked-pointer device with a proximal surface of the gap controldevice.

In Example 39, the subject matter of any one or more of Examples 37-38optionally include wherein marking the digital reference locationcomprises recording a tracked location of the gap control device usingtracking capabilities attached to the gap control device.

In Example 40, the subject matter of any one or more of Examples 37-39optionally include manually positioning a posterior resection guide onthe gap control device.

In Example 41, the subject matter of any one or more of Examples 37-40optionally include wherein digitizing the distance between a proximalresection surface of the tibia and an unresected posterior condyle ofthe femur comprises capturing a pose of the femur relative to the tibiawith the first tracking device and the second tracking device.

In Example 42, the subject matter of any one or more of Examples 24-41optionally include converting the digitized reference point tocoordinates in the three-dimensional coordinate system for a location ofthe posterior resection guide; calculating a position of the feature onthe posterior resection guide relative to the robotic arm when theposterior resection guide is coupled to the robotic arm; and moving thefeature of the posterior resection guide mounted to the robotic arm tothe location.

In Example 43, the subject matter of any one or more of Examples 24-42optionally include holding positioning of the tibia relative to thefemur to fix a gap height between the tibia and femur.

In Example 44, the subject matter of Example 43 optionally includeswherein manually determining a position for the posterior resectionguide to perform the posterior resection comprises positioning a gapgauge into a gap between a proximal portion of the tibia and a posteriorportion of the femur.

In Example 45, the subject matter of Example 44 optionally includesmanually positioning the posterior resection guide into engagement withthe gap gauge.

In Example 46, the subject matter of Example 45 optionally includesmanually positioning the posterior resection guide on the gap gauge, thegap gauge comprising a gap checker block.

In Example 47, the subject matter of any one or more of Examples 45-46optionally include manually positioning a flange of the posteriorresection guide into the gap with the gap gauge, the gap gaugecomprising a shim.

Each of these non-limiting examples can stand on its own, or can becombined in various permutations or combinations with one or more of theother examples.

Various Notes

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventor alsocontemplates examples in which only those elements shown or describedare provided. Moreover, the present inventor also contemplates examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

The claimed invention is:
 1. A method of positioning a posteriorresection guide in a three-dimensional coordinate system using a roboticarm in order to perform a partial knee arthroplasty, the methodcomprising: connecting a first tracking device for a surgical trackingsystem of the robotic arm to a femur; connecting a second trackingdevice for the surgical tracking system of the robotic arm to a tibia;manually positioning the tibia relative to the femur to a desiredorientation to perform a posterior resection; manually determining aposition for the posterior resection guide to perform the posteriorresection; digitizing a reference point for the posterior resectionguide in the three-dimensional coordinate system for a location of afeature of the posterior resection guide; moving the posterior resectionguide to the location in the three-dimensional coordinate system withthe robotic arm; and resecting a posterior portion of a condyle of thefemur using the posterior resection guide to guide a cutting instrument.2. The method of claim 1, wherein the reference point for the posteriorresection guide in the three-dimensional coordinate system for thelocation of the posterior resection guide comprises a digital referencelocation for the feature of the posterior resection guide on a distalend of the femur.
 3. The method of claim 2, wherein the featurecomprises an anterior tip of the posterior resection guide.
 4. Themethod of claim 3, wherein marking the digital reference locationcomprises engaging a tracked-pointer device with a location on ananterior side of the condyle to be resected.
 5. The method of claim 4,wherein engaging the tracked-pointer device with the location on theanterior side of the condyle to be resected comprises: marking a firstlocation at a distal location of the condyle in extension; and marking asecond location at a posterior location on the condyle in flexion; anddrawing a line through the first and second locations to the location onthe anterior side of the condyle.
 6. The method of claim 3, whereinmarking the digital reference location comprises engaging a thirdtracking device with an analogous feature of a manually positionedposterior resection guide for the feature.
 7. The method of claim 3,wherein marking the digital reference location comprises utilizing athird tracking device coupled to a manually positioned posteriorresection guide.
 8. The method of claim 3, wherein marking the digitalreference location comprises marking a location of a resection guidesurface on a manually positioned posterior resection guide.
 9. Themethod of claim 2, further comprising resecting a distal portion of thefemur after digitizing the reference point for the posterior resectionguide in the three-dimensional coordinate system for the location of theposterior resection guide.
 10. The method of claim 1, wherein thereference point for the posterior resection guide in thethree-dimensional coordinate system for the location of the posteriorresection guide comprises a digital reference location for the featureof the posterior resection guide relative to a proximal surface of thetibia.
 11. The method of claim 10, further comprising resecting aproximal portion of the tibia before digitizing the reference point forthe posterior resection guide in the three-dimensional coordinate systemfor the location of the posterior resection guide.
 12. The method ofclaim 10, wherein the feature comprises a distal surface of theposterior resection guide.
 13. The method of claim 12, whereindigitizing the reference point for the posterior resection guide in thethree-dimensional coordinate system for the location of the posteriorresection guide comprises: digitizing a distance between a proximalresection surface of the tibia and an unresected posterior condyle ofthe femur.
 14. The method of claim 13, wherein manually positioning thetibia to the femur comprises inserting a gap control device between aproximal portion of the tibia and a posterior portion of the femur. 15.The method of claim 14, wherein marking the digital reference locationcomprises engaging a tracked-pointer device with a proximal surface ofthe gap control device.
 16. The method of claim 14, wherein marking thedigital reference location comprises recording a tracked location of thegap control device using tracking capabilities attached to the gapcontrol device.
 17. The method of claim 14, further comprising manuallypositioning a posterior resection guide on the gap control device. 18.The method of claim 14, wherein digitizing the distance between aproximal resection surface of the tibia and an unresected posteriorcondyle of the femur comprises capturing a pose of the femur relative tothe tibia with the first tracking device and the second tracking device.19. The method of claim 1, further comprising: converting the digitizedreference point to coordinates in the three-dimensional coordinatesystem for a location of the posterior resection guide; calculating aposition of the feature on the posterior resection guide relative to therobotic arm when the posterior resection guide is coupled to the roboticarm; and moving the feature of the posterior resection guide mounted tothe robotic arm to the location.
 20. The method of claim 1, furthercomprising holding positioning of the tibia relative to the femur to fixa gap height between the tibia and femur.
 21. The method of claim 20,wherein manually determining a position for the posterior resectionguide to perform the posterior resection comprises positioning a gapgauge into a gap between a proximal portion of the tibia and a posteriorportion of the femur.
 22. The method of claim 21, further comprisingmanually positioning the posterior resection guide into engagement withthe gap gauge.
 23. The method of claim 22, further comprising manuallypositioning the posterior resection guide on the gap gauge, the gapgauge comprising a gap checker block.
 24. The method of claim 22,further comprising manually positioning a flange of the posteriorresection guide into the gap with the gap gauge, the gap gaugecomprising a shim.